In traditional wireless telecommunications systems, transmission equipment in a base station transmits signals throughout a geographic region known as a cell. As technology has evolved, more advanced equipment has been introduced that can provide services that were difficult previously. This advanced equipment might include, for example, an enhanced node B (ENB) rather than a base station or other systems and devices that are more highly evolved than the equivalent equipment in a traditional wireless telecommunications system. Such advanced or next generation equipment may be referred to herein as long-term evolution (LTE) equipment. Devices that might be used by users in a telecommunications network can include both mobile terminals, such as mobile telephones, personal digital assistants, handheld computers, portable computers, laptop computers, tablet computers and similar devices, and fixed terminals, such as residential gateways, televisions, set-top boxes, and the like. Such mobile and fixed devices will be referred to herein as user equipment or UE.
A group of LTE-based cells might be under the control of a single entity known as a central control. The central control typically manages and coordinates certain activities with a group of cells such as scheduling the transmission of broadcast/multicast services from the ENBs under its control to the UEs being served by the ENBs.
Services that might be provided by LTE-based equipment can include broadcasts or multicasts of television programs, streaming video, streaming audio, and other multimedia and non-multimedia content. Such services are commonly referred to as multimedia broadcast multicast services (MBMS). An MBMS might be transmitted throughout a single cell or throughout several contiguous or overlapping cells. A set of cells receiving an MBMS can be referred to as a service area. A service area and a region under the control of a central control do not necessarily coincide. For example, a central control might specify that a first subset of cells under its control will deliver a first MBMS and that a second subset of cells under its control will deliver a second MBMS.
An MBMS may be communicated from an ENB to a UE using point-to-point (PTP) communication or point-to-multipoint (PTM) communication. PTP communication, also known as unicast communication, is similar to conventional cellular network communication in that there is a dedicated radio bearer between the ENB and a UE. PTP communication from the ENB may enable high quality communication with the UE. However, when an ENB communicates with a large number of UEs using PTP communication, a substantial amount of overhead may be required for establishing and maintaining the PTP communications and a substantial amount of the available spectrum may be occupied.
PTM communication may include utilizing a dedicated channel or dedicated carrier to transmit data or services to multiple UEs. While a certain amount of overhead may be required to initiate a PTM communication, the overhead is relatively small and may not vary in relation to the number of UEs. That is, as more UEs utilize the data or services, the overhead required to establish and maintain the broadcast PTM communication remains approximately the same. PTM communications may also improve spectral efficiency as the number of UEs increases because no new transmissions are required for newly added users. In some cases, the quality of PTM communications may be worse than that for PTP communications since there is little or no communication from the UEs to the ENB, and because of power considerations and other factors that may reduce the relative quality of the communication.
Transmission of data or services by PTM communication might be either a broadcast or a multicast. A broadcast is a PTM transmission that is freely available to UEs within range of the transmission. A multicast is a PTM transmission that is available only to UEs that have subscribed to or have otherwise been granted access to the transmission. Hereinafter, the terms unicast, broadcast, and multicast might be used interchangeably to refer to any transmission of data or services from an ENB to one or more UEs.
In some LTE telecommunications networks, data is transmitted in Internet Protocol (IP) packets. The IP packets include headers that contain information about the data carried by the packets. In Internet Protocol Version 4 (IPv4), the header is typically 40 bytes long including the Transport Control Protocol header and Real-Time Protocol header and in Internet Protocol Version 6 (IPv6), the header is typically 60 bytes long including the Transport Control Protocol header and Real-Time Protocol header. Due to this large size, the data in an IP header might be compressed to increase the efficiency of IP packet transmissions. The compression is typically carried out by a software and/or hardware component known as the Packet Data Convergence Protocol (PDCP).